Modern vehicles typically include an on-board electronic system that controls, measures, and provides reports regarding operation of the vehicle's various subsystems. On-board electronic systems may include or otherwise support on-board diagnostic (OBD) services that enable vehicle owners and repair technicians to access diagnostic information or other forms of operational information. As one example, an on-board electronic system of a vehicle may be accessed via an OBD interface in the form of a physical connector. OBD information may be communicated over this OBD interface using a variety of protocols, including ALDL, OBD-I, OBD-1.5, OBD-II, etc.